Bidirectional polyphase multimode converter including boost and buck-boost modes

Abstract

A charging method using a multiphase line voltage for charging an energy storage system (ESS) using a polyphase motor drive circuit communicated to a polyphase motor, the polyphase motor drive circuit including a plurality M of driver stages, one driver stage for each phase of the polyphase motor with each driver stage coupled across the energy storage system, the method including the steps of: (a) determining a charge mode responsive to a comparison of the multiphase line voltage to a voltage of the energy storage system, the determined charge mode including a boost mode when the voltage of the energy storage system has a first predetermined relationship to the multiphase line voltage and the determined charge mode including a boost-buck mode when the voltage of the energy storage system has a second predetermined relationship to the multiphase line voltage; (b) converting, when the charge mode includes the boost mode, the multiphase line voltage to a first charging voltage using a first set of N number of the plurality of driver stages, with N less than M, wherein the first charging voltage is communicated to the energy storage system, and wherein the first charging voltage is greater than the multiphase line voltage; and (c) converting, when the charge mode includes the boost-buck mode, the multiphase line voltage to a second charging voltage using a second set of P number of the plurality of driver stages when in the boost-buck mode, with P greater than N, wherein the second charging voltage is communicated to the energy storage system, and wherein the second charging voltage is less than the multiphase line voltage.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
       1. A charging system using a line voltage for charging an energy storage system (ESS) using a polyphase motor drive circuit communicated to a polyphase motor, the polyphase motor drive circuit including a number M of driver stages, M>1, one driver stage for each phase of the polyphase motor with each driver stage coupled across the energy storage system, the system comprising:
 a configurable converter using a selectable number of the plurality M driver stages to configure one of a boost converter using N, N<M, driver stages and a boost-buck converter using said N driver stages and an additional driver stage of the plurality of M driver stages, said configurable converter including a first charging capacitance coupled across the ESS and a second charging capacitance coupled across the ESS and further including N number of boost inductances coupling the line voltage to said N driver stages and a boost-buck inductance coupling said additional driver stage to said second charging capacitance; 
 a first selector selectively coupling said driver stages and said first capacitance to the ESS and to said second capacitance, said first selector coupling said driver stages and said first capacitance to the ESS and to said second capacitance for said boost converter and interrupting said coupling of said driver stages and said first capacitance 
 to the ESS and to said second capacitance for said boost-buck converter; 
 a second selector selectively coupling said additional driver stage to said boost-buck inductance, said second selector interrupting said coupling of said additional driver stage to said boost-buck inductance for said boost converter and coupling said additional stage to said boost-buck inductance for said boost-buck converter; and 
 a controller, coupled to said selectors and to the M driver stages and responsive to a comparison of the line voltage and a voltage of the ESS, configuring said selectors for said boost converter and said configurable converter as said boost converter when said comparison determines the line voltage is less than said voltage of the ESS and configuring said selectors for said boost-buck converter and said configurable converter as said boost-buck converter when said comparison determines the line voltage is greater than said voltage of the ESS, said controller operating said N driver stages without said additional stage to up-convert the line voltage to a first charging voltage when charging the ESS using said boost converter, and said controller operating said N driver stages and said additional driver stage to convert the line voltage to a second charging voltage when charging the ESS using said boost-buck converter. 
 
     
     
       2. The charging method of  claim 1  wherein the polyphase motor includes a winding associated with each phase with each said winding including a winding inductance and wherein said boost-buck inductance includes one of said winding inductances. 
     
     
       3. The charging system of  claim 1  wherein M is 3 and N is 2. 
     
     
       4. The charging system of  claim 1  wherein each of the M driver stages includes a semiconductor motor driver stage.